Shrink-head casing for ingot molds



Dec. 10, 1929. E GATHMANN- 1,739,222

SHRINK HEAD CASING FOR INGOT MOLDS Filed July 14. 1928 INVENTOR ATTORNEYS '5 material, and 'more particularly tofore also been granted to 40 qualities 45 proximately Patented Dec. 10, 1929 7 UNITED STATES PATENT OFFICE EMIL GATHEMANN, OF BALTIMORE, MARYLAND SHRINK-HEAD CASING FOR IN GOT MOLDS Application filed July 14,

This invention relates broadly to the art casting steel ,ingots in metallic molds equipped with shrink head or feeder casings made of refractony and of heat-insulating to an improvement in the type of construction of said shrink head casings. g

In several U. S. LettersPatents heretofore granted to me,No. 1,643,241 for instance, Ihave 10 shown molds for casting steel ingots in which provision is made for conserving the heat of the molten metal at the top of the ingot and for cooling said .ingotbr' casting from the bottom upwardly. *A moldof' the type de la-scribed'in the aforen'amed, Letters Patent,

when used in connection with the improved type of shrink head. casing described in the present application, will produce a physically sound ingot body with a greatly les- 29 sened percentage of shrink head volume, as

I am thereby enabled to'maintain the molten steel forming the uppermost or shrink head portion of the ingot in a fluid condition until 'the metal composing has cooled and solidified progressively from the body of the ingot the lower portion 'to the to United States Letters atents have hereme for improve ments in shrink head casings and I refer 3 specifically to Patents N 0. 1,258,209 of March 5, 1918, and No. 1,508,931 of September 16, 1924, and No. 1,696,395 of December 25, 1928. While the shrink head casings heretofore known inthe art have been satisfactory either as refractories or as conservers of heat,

they have not had these qualities combined in an inexpensive'unit structure suitable for use in commercial ingot production.

Because of the inefficient heat-insulating of the shrink head casings heretofore used, the common practice, since the grant of my Patent No. 1,049,57 3 of January 7, 1913, has been to employ shrink head casings having a chamber volume equal to apof the total ingot, altho the actual shrinkage of well-deox'idized, high carbon steel from the liquid to the solid state has been ascertained to average-but 3% of the ingot volume when the metal is teemed O at suitable temperature. Therefore, a rel 1928. Serial No. 292,703.

atively high percentage of steel is wasted in the shrink head in order to insure of soundness in the ingot body.

Means have been proposed for pre-heating the walls of the shrink head casing and the upper part of the ingot mold chamber in order to lessen the required volume of the shrink head chamber, but the apparatus required is too cumbersome and expensive for tonnage production and has been used to a very limited extent.

The primary object of my invention is to provide a shrink head casing of unit structure, the exterior walls of which are relatively strong and highly refractory and the interior or core portion of which is formed of a cellular material, the air cells of which prevent the conduction and the radiation of the heat of the molten metal contained within the shrink head.

' My improved shrink head or feeder comterial forming thejouter casing, is a much better insulator and heat conserver than said casing material. 'I thus obtain a mold top or feederhaving the heat-insulating qualities essential to eflicient shrink head construction without sacrificing the important factor of strength of a high refractory structure.

In the accompanying drawings:

Figure 1 shows a longitudinal section of a shrink head casing constructed in accordance with my invention. 7

Figure 2 is a cross sectional view on line 22 of Figure 1, and

-Figure 3 is a vertical central section'of an ingot mold fitted with a shrink head casing of'the type shown in Figure 1, a solidified ingot being contained therein.

Referring to Figures 1 and 2 of the drawings, the shrink head casing 5 consists of an inner or core portion 7 formed of a material having a high heat insulating value, this material being of a very open or cellular structure, such as infusorial earth, diatomite or the like. Surrounding the core portion 7 is a casing 8, having inner walls 9 and outer walls 10, the casing 8'being formed of highly refractory material, the preferred material being fire clay having a sintering point ap proximately equal to or in excessof the temperature of liquid steel.

Figure 3 illustrates a Gathmann big-end up type of mold l fitted with a feeder or mold top 5 of the type shown in Fi ures 1 and 2. A solidified ingot 2 is graphically illustrated therein. The mold has side and bottom walls 3 and 3 and is supported by a stool or plate 4. A quantity of heat-conserving material 6 shown on'the top of the ingot within the srink head casing prevents the radiation of heat from the top of the ingot, thereby aiding in the progressive sodidifioation of the metal from the bpttom upwardly,

In manufacturing my improved shrink head casing, I preferably first form ormold the inner or core portion into the desired shape and suitably dry or bake it. I then form or mold around the core portion the casing 8 ofhighly refractory fire clay. I make the walls of the casing 8 relatively thin as compared to the total thickness of a wall of the completed shrink head casing; but since the core portion 7 has little mechanical strength, I preferably make the walls of the" casing 8 of suflicient thickness to give the shrink head casing as a whole the necessary rigidity and structural strength to withstand handling and shipping without undue breaka e.'

After the outer casing 8 has been formed ;so as to surround the core portion 7-, the complete shrinkhead casing is placed in a kiln for burning or baking and thus hardening the fire clay casing 8. During'the kiln drying or burning operation the outer casing becomes denser as it hardens, While the inner or core portion 7 becomes even more porous than it was hen first formed. 4

I preferably make the height of my improved shrink head casi-ng somewhat greater than the average inside diameter of the shrink head casing chamber 11. A a result of so apportioning the dimensions of my shrink head casing and due to the superior heat conserving qualities of the core portion of said casing I am enabled to make the volume of the chamber of the shrink head casing equal to approximately only 8% to 10%0f the total volume of the ingot in the molding of which the casing is used.

As stated in my U. S. Patent of April 30, 1929, when using my improved shrink head casing, and a metallic mold, I am enabled to reduce the percentage of the solidified metal'in the shrink head to as little as 5% of the volume of the entire solidified inot. It is then apparent that by thus constructing a shrink head casing, the core portion of which is very porous and the outer walls or the matrix of which are highly refractory and relatively strong, I am enabled to greatly reduce the volume of the chamber of the I shrink head casing, thereby effecting a very 1. A shrink head casing for ingot molds M comprising a core of highly heat-insulating but structurally weak material and inclosing refractory walls that are of a stronger structure and which are self-supporting.

2. A self-supporting shrink head casing for ingot molds 1 comprising a structurally weak core of high heat-insulating cellular material supported by inclosing walls of refractory material as and for the purpose specified.

3,' shrink head casing for'ingot molds comprising a porous core of highly heat-insulating material and outer walls which are highly refractory and relatively strong and self-supporting ,4, A shrink headcasing for ingot molds comprising outer walls of 7 strong self-supporting fire clay and a core of cellular material which is relatively weak andwhich possesses relatively high heat-insulating propv erties as compared with the outerwalls which inclose it.

5. A shrink headcasing for ingot molds comprising outer walls of fire clay and noncombustible core of cellular material which is relatively weak, but which possesses relatively high heat-insulating properties as compared to the outer walls which inclose it.

In testimony whereof, I have hereunto subscribed my name.

EMIL GATHMANN 

